Definition

Type 2 Diabetes (Non-Insulin Dependent)

Type 2 (non-insulin dependent) diabetes is characterized by insufficient insulin receptors to effect proper glucose control after insulin is released (insulin resistance). Those affected typically have a body habitus in which there is increased abdominal girth, often described as an "apple" shape. The reason for this is that the highest concentration of insulin receptors is located in the abdominal rectus muscles and the increased layer of fat appears to impair insulin receptor sensitivity.

The patient has increased hunger due to excess insulin release as a result of elevated glucose levels. This insulin release further decreases insulin receptors due to elevated hormonal levels, and thus a vicious cycle begins of excessive appetite with weight gain. Otherwise, these patients exhibit few symptoms, with the possible exception of poor wound healing and fatigue.

Type 2 diabetics are not ketosis-prone due to the presence of insulin, but do develop a condition of hyperglycemic hyperosmolarity during pregnancy, generally after an episode of vomiting and diarrhea in which the patient replaced fluids with glucose solutions. This condition has a high morbidity for the fetus, but can be effectively treated with immediate fluid replacement.

Also included in this classification is "secondary diabetes." Secondary diabetes is carbohydrate intolerance secondary to pancreatic disease, excess production of certain hormones (eg, growth hormone), use of certain drugs (eg, corticosteroids), insulin receptor abnormalities, and certain genetic disorders.

Genetics of Inheritance

Type 2 diabetes is not linked to HLA or genetic markers, but evidence supports a genetic component. With type 2 diabetes, the risk of frank diabetes in a first-degree relative is almost 15%, and about 30% more will have impaired glucose tolerance. If both parents have type 2 diabetes, the incidence of diabetes in the offspring is 60-75%. Monozygous twins have a much greater propensity for type 2 diabetes (almost 100%) than for type 1 diabetes (20-50%).

Significance

Type 2 diabetes has a major impact on the morbidity and mortality of the individual as well as on the quality of life (eg, amputation of extremities, blindness, strokes). Controlling glucose minimizes the onset of these complications and reduces the progression of existing ones. Education about glucose control has been shown to have a major impact on the patient's overall health.

Treatment

Type 2 diabetes is treated primarily by lifestyle modification. The level of dietary fat is decreased and the ingestion of soluble fiber increased. Increased exercise, with particular attention to the abdominal muscles, is also advised. Oral hypoglycemic agents are used in nonpregnant patients, but are not yet widely used during pregnancy.

If weight loss can be accomplished and pregnancy delayed, maintaining a woman on oral agents can be advantageous preconceptionally to reduce insulin resistance. Preconception evaluation is the same as in type 1diabetics. It is surprising that the incidence of initial renal disease detected is higher, probably due to a longer asymptomatic period prior to diagnosis. Insulin is generally used during pregnancy and perhaps even during conception. Also during pregnancy, the health care team emphasizes diet and daily exercise.

Soluble fiber is a key in therapy of type 2 diabetes since it reduces the glycemic intake of the diet, thus reducing insulin release, which results in heightened sensitivity of insulin receptors. Fat intake is closely monitored because it reduces insulin sensitivity and often has been the main source of calories for these obese persons. Thus when fat intake is decreased and portion size increased, the patient is unable to maintain weight during the increased metabolic demand of pregnancy. The dietitian must work closely with the individual and monitor actual calorie intake to allow a minimum of 15 pounds of weight gain, even in the massively obese patient, for proper nutrition in pregnancy.

Exercise is initiated, and increased water intake prior to and during the exercise period is stressed. Swimming is the safest exercise for the massively obese to minimize trauma to joints, but walking and/or upper arm ergometrics or stationary bicycling are excellent alternatives.

Insulin therapy is added in small amounts, with emphasis on long-acting insulin. In the past, many type 2 diabetics received very high doses of insulin. This was not only unnecessary but hazardous, because it resulted in significant downregulation of insulin receptors.

The remainder of therapy, such as glucose monitoring and evaluation of the fetus, is similar to that done in type 1 diabetic management. Emphasis is placed on ultrasonography to assess fetal growth due to anatomic limitations in assessing fundal growth. Unfortunately, fetal weight assessment is often inaccurate in this group of individuals, due to the fat distribution in the pannus region.

When the patient is in labor, it is extremely important to administer a controlled glucose infusion to meet the body's energy needs. Yet it is rare to need an insulin infusion due to the high metabolic demand with a limited amount of glucose. For the postpartum patient, early ambulation assists in decreasing thromboembolic risks. Often glucose control is achieved postpartum on no more than an ADA diet. If hypoglycemic agents are necessary postpartum, insulin is continued for those who are breastfeeding, whereas the oral agents may be used in the nonbreastfeeding mothers. Postpartum weight loss is encouraged (see following section on Gestational Diabetes). Preconception evaluation prior to the next pregnancy is stressed.

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